Santa Monica will always be a desirable place to live, and will generally appeal to a young, affluent renter. The Santa Monica apartment rental market is still very strong, and steady. Depending on where your property is, will determine what the market rents should be. Generally, rents have not changed in the last 6 months. They are holding firm. I would browse WestsideRentals.com and Craigslist.org to see what your neighbors are renting for.